10 



of the brain, yet may be influenced through the brain, the office of 

 which is considered as purely sensorial. The separate existence of 

 these powers is illustrated by a review of the various classes of ani- 

 mals, in the lowest of which we find only the muscular system ; in 

 the next above the muscular and nervous without sensorium ; and in 

 the most perfect animals we find the three vital powers combined, 

 each having existence not immediately depending on the others, but 

 so connected that no one can subsist long without the others, since 

 all are supported by the same circulation, that is dependent for its 

 continuance upon muscular action, which cannot exist without re- 

 spiration, while this again depends on the nervous system for its 

 continuance. 



Although the heart of a frog retains its power long after the brain 

 and spinal marrow are removed, nevertheless Dr. Philip found that 

 its force may be for a time extremely impaired, by suddenly crushing 

 the brain or spinal marrow, but it will again recover its power after 

 the entire destruction of those parts ; and corresponding effects were 

 observed, though not so distinctly, in rabbits. 



It is to this cause that the author ascribes the difference between 

 his results and some of those of M. Le Gallois, who, instead of em- 

 ploying a small wire to destroy the spinal marrow, used an instru- 

 ment which fitted the cavity of the spine, and consequently crushed 

 the marrow more suddenly. 



From the whole of his experiments the author concludes, that the 

 involuntary muscles obey the same laws as those of voluntary motion; 

 that the difference arises from their being under different stimuli ; 

 that both are liable to be stimulated through the nervous system; that 

 they each have power independent of that system. That what has 

 been called nervous system consists of two parts, one purely sensorial, 

 the other conveying impressions. 



That the three powers are combined in the most perfect animals. 

 That the muscular may be destroyed through the nervous system, and 

 the nervous through the sensorial ; and though each is not strictly 

 dependent on the others, they are so connected that no one can exist 

 long without the others. 



Experiments to ascertain the Influence of the Spinal Marrow on the 

 Action of the Heart in Fishes. By Mr. William Clift. Communi- 

 cated by Sir Everard Home, Bart. V.P.R.S. Read February 16, 

 1815. [Phil. Trans. 1815, p. 91.] 



These experiments were undertaken by the author, in order to as- 

 certain the truth or fallacy of M. Le Gallois' conclusion respecting 

 the action of the heart being dependent on the spinal marrow. For 

 since the death of quadrupeds (on which M. Le Gallois operated) is 

 so readily produced by injury to the vital organs, it appeared to 

 Mr. Clift that fishes would be far preferable, from their being more 

 tenacious of life. 



After two or three preliminary experiments on the duration of the 



